The wear-resistant steel plate is widely used for mechanical products for use in engineering, mining, agriculture, cement production, harbor, electric power, metallurgy and the like wherein operating conditions are particularly awful and high-strength as well as high wear resistance properties are required. For example, bulldozer, loader, excavator, dump truck and grab bucket, stacker-reclaimer, delivery bend structure, etc. may be mentioned.
In recent decades, the development and application of wear-resistant steel grows quickly. Generally, carbon content is increased and suitable amounts of trace elements such as chromium, molybdenum, nickel, vanadium, tungsten, cobalt, boron, titanium and the like are added to enhance the mechanical properties of wear-resistant steel by taking full advantage of various strengthening means such as precipitation strengthening, fine grain strengthening, transformation strengthening and dislocation strengthening, inter alia. Since wear-resistant steel is mostly medium carbon, medium-high carbon or high carbon steel, increase of carbon content leads to decreased toughness, and excessively high carbon content exasperates the weldability of steel badly. In addition, increase of alloy content will result in increased cost and degraded weldability. These drawbacks refrain further development of wear-resistant steel.
Notwithstanding the wear resistance of a material mainly depends on its hardness, and toughness has significant influence on the wear resistance of the material, too. Under complicated working conditions, good wear resistance and long service life of a material can not be guaranteed by increasing the hardness of the material alone. Adjusting the components and thermal treatment process, and controlling the appropriate matching between the hardness and toughness of low-alloy wear-resistant steel, may result in superior comprehensive mechanical properties, so that the requirements of different wearing conditions may be satisfied.
Welding is a greatly important processing procedure and plays a vital role in engineering application as it can realize joining between various steel materials. Weld cold cracking is the most common welding process flaw. Particularly, cold cracking has a great tendency to occur when high-strength steel is welded. Generally, preheating before welding and thermal treatment after welding are used to prevent cold cracking, which complicates the welding process, renders the process inoperable in special cases, and imperils the safety and reliability of the welded structure. For high-strength, high-hardness, wear-resistant steel plates, the welding-related problems are particularly prominent.
CN1140205A has disclosed a wear-resistant steel having medium carbon and medium alloy contents, the contents of carbon and alloy elements (Cr, Mo, etc.) of which are far higher than those of the present invention. This will inevitably lead to poor weldability and machinability.
CN1865481A has disclosed a wear-resistant bainite steel which has higher contents of carbon and alloy elements (Si, Mn, Cr, Mo, etc.) and poorer weldability and mechanical properties in comparison with the present invention.